As usage of the Internet has increased, various web sites have responded by adding such features as redundancy and load balancing. Accordingly, it has become important to direct a client to the geographically closest and least busy web site. The practice of dispersing data from a web site closer to the client is referred to as “client proximity” and has been widely accepted.
In an attempt to direct clients to the geographically closest and least busy web site, a number of techniques have been implemented. Current technologies that attempt to provide a measure of geographic distribution of Web requests rely primarily on Domain Name System (DNS) techniques; namely, techniques normally performed by a Domain Name System (DNS) server alone or in combination with other logic.
One prior technique is Round-Robin Domain Name System (DNS). This technique involves entering multiple IP addresses to represent a single DNS hostname. As clients resolve the hostname, DNS responds by cycling through the multiple listed IP addresses.
Another technique involves computation of routing metrics by the DNS server and these metrics being used to determine how far away a client is from various web sites forming the global domain. This allows the DNS server to answer a DNS request with a web site address associated with a local domain considered to be closest to the client. The primary DNS server can determine the distance from the client to each web site by counting network hops.
Another technique involves the use of a DNS server in conjunction with routers to approximate network distance to a web site from the requester. This technique is achieved through the announcement of a single IP address or a single set of IP addresses throughout the Internet resolving to a single hostname.
Yet another technique involves geographically distributed DNS servers that provide differing IP addresses on a per server basis. This technique is achieved through the announcement of a single IP address for authoritative DNS servers, which when queried may each provide a different response specifying the nearest web site.
While these DNS techniques provide some load sharing capabilities, they are inherently problematic because they are difficult and resource-intensive to resolve. In addition, the DNS solutions are incapable of being content aware and are, at best, useful in assisting a more robust approach by initially guiding a client to a web resource.
There are now attempts to develop a client proximity selection process using personal content directors (i.e. site selectors) in which clients are directed to “chronometrically optimal” locations, namely locations that provide the best overall response time, taking into account all factors including network topology (latency), server response time and the like. Exemplary client proximity processes are described in a commonly-owned, U.S. patent application Ser. No. 09/728,305 (filed Nov. 30, 2000) and a concurrently filed U.S. Patent Application entitled “A Method and Apparatus For Discover Client Proximity Using ILX Translations” (App. No. 10/027,686).
During “Refresh”, “Image Insert” and even “ILX” modes of operation, the client proximity process uses HTTP redirects to enable a client to point at another site after client proximity computations have completed. The use of HTTP redirects, being additional overhead, pose many disadvantages. For illustrative example of an HTTP redirect is set forth below in Table 1.
TABLE 1HTTP RedirectHTTP HeaderContentsStatus LineHTTP/1.1 307 (for version 1.1clients)HTTP/1.0 302 (for version 1.0clients)General HeaderCache-Control: PrivateConnection: CloseDate: <GMT Date>Response HeaderServer: <name of this Internet SiteSelector>Pad: <pad characters>Location:HTTP://wwwa.nortelnetworks.comExpires: <GMT + configurable time>Content-Length: xContent-Type: text/html
For instance, HTTP redirects cause additional traffic over the network and additional latency to complete these Transmission Control Protocol (TCP) connections. In addition, HTTP redirects are also visible by the client viewing his or her browser, which may be undesired by the web site owners. Also, bookmarks to a selected site after the client proximity computations may preclude such client proximity computations to be performed for that client in the future.
For streaming media environments, the overhead associated with redirects is small in comparison with the amount of information downloaded. While redirects are supported by the RTSP protocol used by QUICKTIME® players by Apple Computer of Cupertino, Calif. and REALPLAYER® by RealNetworks of Seattle, Wash., they are not supported by the MICROSOFT® Media Services (mms) protocol. A technique that can be utilized by many streaming video protocols is desired.